Myofibrillar myosin ATPase activity in hindlimb muscles from young and aged rats
Myofibrillar myosin ATPase activity in hindlimb muscles from young and aged rats
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DOI：
10.1016/j.mad.2004.07.002
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发表时间：
2004-09-01
影响因子：
5.3
通讯作者：
Thompson, LV
中科院分区：
文献类型：
--
作者：
Lowe, DA;Husom, AD;Thompson, LV
我们测试的假设，钙激活的肌球蛋白ATP酶活性是较低的老年大鼠的肌肉相对于年轻大鼠的肌肉，独立的肌球蛋白亚型表达的变化。从年轻（8-12个月）和老年（32-38个月）F344 x BN大鼠的比目鱼肌、跖肌和半膜肌的透化纤维制备肌原纤维，并测定静息肌球蛋白ATP酶、Ca 2+激活的肌球蛋白ATP酶以及肌球蛋白重链（MHC）和肌球蛋白轻链（MLC）同种型组成。静息肌球蛋白ATP酶不受年龄的影响（P > 0.42）。比目鱼肌和跖肌肌原纤维的Ca 2+激活的肌球蛋白ATP酶不受年龄的影响（P > 0.31），但老年大鼠的半膜肌肌原纤维中的Ca 2+激活的肌球蛋白ATP酶（0.448 +/- 0.019 Rmol Pi/min/mg）比年轻大鼠（0.533 +/- 10.031 mumol Pi/min/mg; P = 0.03）低16%。相应地，老年大鼠的单个半膜肌纤维的最大无负荷缩短速度（4.6 +/- 0.2纤维长度/s）比年轻大鼠的纤维（5.8 +/- 0.3纤维长度/s; P < 0.01）慢。在任何肌肉中均未检测到MHC或调节MLC亚型的年龄相关变化（P>或等于0.08），但在跖肌和半膜肌中发生了基本MLC的变化。这些数据表明，钙激活的肌球蛋白ATP酶活性随着年龄的增长而降低，在半膜肌，独立的年龄相关的变化，MHC亚型的表达，是一种机制，有助于与年龄相关的肌肉收缩放缓。(C)2004爱思唯尔爱尔兰有限公司保留所有权利。
We tested the hypothesis that Ca2+-activated myosin ATPase activity is lower in muscles of aged rats relative to muscles of young rats, independent of changes in myosin isoform expression. Myofibrils were prepared from permeabilized fibers of soleus, plantaris, and semimembranosus muscles of young (8-12 months) and aged (32-38 months) F344 x BN rats and assayed for resting myosin ATPase, Ca2+ activated myosin ATPase, and myosin heavy chain (MHC) and myosin light chain (MLC) isoform compositions. Resting myosin ATPases were not affected by age in any muscle (P > 0.42). Ca2+-activated myosin ATPases of soleus and plantaris myofibrils were not affected by age (P > 0.31) but were 16% lower in semimembranosus myofibrils from aged rats (0.448 +/- 0.019 Rmol P-i/min/mg) compared to young rats (0.533 +/- 10.031 mumol Pi/min/mg; P = 0.03). Correspondingly, maximal unloaded shortening velocity of single semimembranosus fibers from aged rats was slow (4.6 +/- 0.2 fiber lengths/s) compared with fibers from young rats (5.8 +/- 0.3 fiber lengths/s; P < 0.01). No age-related changes in MHC or regulatory MLC isoforms were detected in any muscle (P greater than or equal to 0.08) but changes in the essential MLC occurred in plantaris and semimembranosus muscles. The data indicate that Ca2+-activated myosin ATPase activity is reduced with age in semimembranosus muscle, independent of age-related changes in MHC isoform expression, and is one mechanism contributing to age-related slowing of contraction in that muscle. (C) 2004 Elsevier Ireland Ltd. All rights reserved.